! EXAM04.
!    1-A-1 CH2    TCSCF calculation on methylene.
!    The wavefunction has two configurations, exciting
!    the carbon sigma lone pair into the out of plane p.
!
!    Note that the Z-matrix used to input the molecule
!    can include identifying integers after the element
!    symbol, and that the connectivity can then be given
!    using these labels rather than integers.
!
!    This job tests the GVB wavefunction and gradient.
!
!    The initial GVB-PP(1) energy is -37.187342653.
!    The FINAL energy is -37.2562020559 after 10 iters.
!    The GVB CI coefs are 0.977505 and -0.210911, giving
!    a pair overlap of 0.64506.
!    Mulliken, Lowdin charges for C are 0.020810, 0.055203.
!    The dipole moment is 1.249835.
!    The RMS gradient = 0.019618475.
!
 $CONTRL SCFTYP=GVB  RUNTYP=GRADIENT  COORD=ZMT  $END
 $SYSTEM TIMLIM=1 $END
 $BASIS  GBASIS=STO NGAUSS=2 $END
 $SCF    NCO=3  NSETO=0  NPAIR=1  $END
 $DATA
Methylene...1-A-1 state...GVB...one geminal pair...STO-2G
Cnv  2

C1
H1  C1 rCH
H2  C1 rCH  H1 aHCH

rCH=1.09
aHCH=99.0
 $END
! normally a GVB-PP calculation will use GUESS=MOREAD
 $GUESS  GUESS=HUCKEL  $END

Link to the log file of this example.
exam04 Log File